Process of separating crystalline wax, amorphous wax, and lubricating oil from wax slop



w. s. BAYLls 1,939,946

AMORPHOUS AND LUBRICATING OIL FROM WAX SLOP Dec. 19, 1933.

PROCESS OF SEPARATING CRYSTALLINE WAX,

WAX

Filed Feb. l1, 1929 ree f (3.4 .c/.s

Trae/Vey.

Patented Dec. 19, 1933 UNITED STATES PROCESS OF SEPARATING CRYSTALLINEWAX, AMORPHOUS WAX, AND LUBRICAT- ING OIL FROM WAX SLOP Walter S.Baylis, Los Angeles, Calif., assignor to Filtrol Company of California,Los Angeles, Calif., a corporation of California Application February11, 1929. Serial No. 339,030

9 Claims. (Cl. 196-17) This invention relates to a process having theobject of separating both crystalline and amorphous wax and recovering amaximum yield of lubricating oil from Wax slop. At the present time, aso-called Wax slop cut is produced during the process of distillingcrude petroleum Aso oils in such practice where an intermediate cutbetween the wax distillate cut and the cylinder stock cut is made. Atthe present time, there is no known method of treating this stock andseparating the wax without cracking, for the reason that the stockcontains a mixture of both crystalline and amorphous wax which preventseither cold' settling, pressing or centrifuging. This condition is dueprincipally to the presence of so-called inhibitors principally of acolloidal nature. By amorphous wax, I mean solid substances which do notcrystallize and area, without dente characteristic shape.

By the practice of my process, I am able to separate colloidalinhibiting and coloring matters, and to so change the character of thewax as to permit it to be readily separated .from the stock without anysubstantial cracking and with practically the theoretical yield of ahigh-grade lubricating oil of low cold test. f

The accompanying drawing shows, more or less diagrammatically, anapparatus suitable for carrying out the process. serve. In the drawing,10 indicates a still fitted with an agitator 11 and adapted to serve asa steam stil1,`this still being preferably constructed as a verticalstill mounted upon a Dutch oven. It isprovided with a steam inlet pipe11a, entering the still at the top and being carried down close to thebottom, a vapor outlet pipe 13, and av bottom discharge pipe 14 having Acontinuation 20 of the vapor pipe 13 is connected to an atmosphericcondenser -21. A pipe 22 connects the atmospheric condenser 21 withreceiving tanks 23 and 24, respectively, and is provided with a valve75.

In the pipe 22, between the atmospheric condenser 21 and receiving tanks23 and 24, is a water-separating device 22a for the purpose ofseparating condensed steam from the distillate.

Other apparatus will A pipe 19a connects the- A pipe 57 connects thereceiving tank 23 to a vacuum-creating device 58 whichwmay. be a steamejector or vacuum pump, said pipe having a branch 59 connecting thereceiving tank 24 with the pipe 57. The pipe 57 has a valve 60 and thebranch-pipe 59 has a valve 6l.

In the pipe 22, just before it enters theyreceiving tanks 23 and 24, areplaced valves 62 and 63. The pipe 14, containing the valve 15, connectsthe bottom of V the still 10 toY the suction of a lter-press pump 25. Apipe 26 connects the discharge. of the pump 25 to the inlet of a iilterpress 27 containing filter plates 28. A collecting pipe 29 connects thedischarge of the lter press 27 to cooling tanks 30 and 31. This pipecontains valves 32 and 33. 'Ihe cooling tank 30 is connected to amanifold pipe 34 by means of a pipe 35 containing a valve 36. Thecooling tank 31 connects with the manifold pipe 34 by means of a pipe 37containing a valve 38. The manifold pipe 34 is connected to the suctionend of a pump 39. The discharge end of the pump 39 is connected to afilter press 40 containing lter plates 41 by means of a pipe 42. Thedischarge of the filter press 40 is adapted to be cooled by means of arefrigerating system 43, and is led thereto by a pipe-43a,. The entirepress may be located in a cold-room or otherwise refrigerated. Therefrigerating system 43 is connected by a pipe 44 to the basket of acentrifugal machine 45. The centrifugal machine is connected by a pipe46 to Wax-storage tanks 47, and is also connected by a pipe 48 tostorage tanks 49. A tank 50 is a charging tank for a solvent diluent andis connected by means of a pipe 51 to the cooling tank 31. This pipecontains a valve 54. A branchpipe 52 connects the pipe 51 with thecooling tank 30 and contains a valve 53. A pipe 55 containing a valve 56is adapted to deliver solvent from pipe 51 to the pipe 43a at a pointjust before the latter enters the refrigerating system.

A pipe 65 having valves 66 and 67 connects the pipes 22 and 29. A pipe68 connects the receiving tank 30 to a vacuum creating device 69 whichis similar to vacuum creating device 58. 'Ihe pipe 68 is provided withvalves 70 and 71. The pipe '72 connects the vacuum creating device 69with tank 31 and is provided with valves 73 and 74.

The operation of my' process using the abovedescribed apparatus is asfollows:

The still 10 is rst lled with a suitable charge of the oil stock to betreated through nsL the pipe 17. To this charge of oil stock is addedfrom two to ten per cent of its weight of powdered mineral adsorbent,preferably of the acidactivatedclay type which is introduced intothestill through the inlet 16. I prefer to use the kind of acid-activatedclay known commercially as Filtrol, which is an acid-activated clay madeby a process somewhat similar to that disclosed in United States Patentto Prutzman, No. 1,397,113, issued November 15, 1921.

The agitator 11 is then started to thoroughly mix the two substances andafter a suitable period of mixing, superheated steam at a temperature offrom 500 to 700 F. is turned on through the pipe 11a. The valves 15,16a, and 17a are closed during this operation. Vacuum may or may not beapplied, as desired, by means of the pump or ejector 58. The temperatureis raised and steam distillation is now carried on until approximatelyfrom i'ifty to sixty per cent by weight of the charge in the still 10has been distilled overhead and collected in either one of the receivingtanks 23 or 24. Distillation is carried on until the still bottoms havebeen concentrated to a desired viscosity, the viscosity of these bottomsbeing dependent upon the character of the raw stock being treated andthe kind of oil or wax desired.

The overhead fraction contains light distillates with a large percentageof crystalline wax, and is condensed by means of the air condenser 21and collected in either of the receiving tanks 23 or 24. This fractionis allowed to stand in storage in the receiving tanks 23 or 24, with orwithout artificial cooling as desired, for a period of time until thewax has crystallized out. The material is then in condition to betreated by well-known methods, for the removal of the Wax in the samemanner as wax is removed from a wax distillate cut and the manufactureof light lubricating oils from the residues. After the distillation hasbeen carried to this point it is stopped and valves 16a, 17a, and 15 areopened, the pump 25 started, and the still bottoms of asphaltic, waxy,and adsorbent material remaining in the still 10 are pumped through thepipe 14 by means of the pump 25, and through the pipe 26, into the lterpress 27 where the adsorbent material is removed, preferably at 275 F.

The filtrate from the press 27 flows through the pipe 29 into the tanks30 and 31 which are equipped With means for cooling. 'Ihe charge offiltrate in either of the tanks 30 or 31 is now diluted with gasoline,distillate, or any other suitable solvent from the tank 50, through thepipe 51, and` in the case of tank 30, also through the branch-pipe 52.This dilution is in the ratio of approximately sixty per cent of solventto forty per cent filtrate. The charge is cooled to between 40 and 60 F.During this cooling operation, crystalline wax with very little, if any,amorphous wax will separate out. When a. suflicient length of time haselapsed to permit the Wax to form, the Wax structure is mechanicallybroken up and a charge from the cooling tank 30 and/or 31 is dischargedthrough the manifold 34 into the suction end of the pump 39, from whenceit is discharged through the pipe 42 into the preferably precooledfilter press 40, in which press the crystalline wax is removed.

The filtrate from the press 40 is discharged through the pipe 43a intothe refrigerating system 43, in which the mixture of oil and solvent iscooled to approximately 40 F. It is preferably further diluted bysolvent from pipe 55 before it enters the refrigerating system. Aftercooling to this point, the charge is conducted through the pipe 44 tothe centrifugal machine 45, where the amorphous wax is separated, fromwhich it passes through the pipe 46 to the storage tank 47, the de-Waxedoil and solvent passing through the pipe 48 to the storage 49. This oiland solvent mixture is then ready to be subjected to distillation forthe purpose of driving off the solvent and yielding the lubricating oilas residue. For this purpose Well-known standardized types of re-runapparatus may be used.

The oil fraction distilled from the still l0 contains crystalline waxwith little or no amorphous wax. The still bottoms from this operation,after filtration to remove the adsorbent material, contain amorphous waxwith a very small amount of crystalline wax. This effect ofsubstantially complete removal of the crystalline wax is not obtainedwithout the presence of the adsorbent material in the still duringdistillation, unless the oil is cracked. Cracking destroys valuablelubricating material and is therefore undesirable here. The rate ofdistillation affects the separation of crystalline and amorphous wax.Therefore, it is desirable to carry the distillation on as rapidly aspossible and at as low a temperature as possible,-hence the desirabilityof as high a Vacuum as possible. Cracking is substantially avoided bythe presence of the adsorbent material in the still and by rapiddistillation with superheated steam, with or without the aid of reducedpressure.

It lies within the purview of my invention to distill the wax slopcompletely; that is, to dryness in the still 10 in the presence of theadsorbent. I have found that in such operation no sticky residue, butrather a loose, dry powder is formed. In such distillation, the rstfifty per cent to sixty per cent of distillate is run to storage, asusual, to give the crystalline wax time to form, and this wax isseparated in the same manner as described in the foregoing matter. Thebottom cut is distilled to dryness without breaking the vacuum orinterrupting the steam supply, and may be run directly into the tanks 30and 31 by means of pipes 22, 65 and 29. Before the valves 66 and 67 areopened, and the valve 75 closed, the vacuum creating device 69 isstarted, and the valves to the proper tank opened. Dilution in thesetanks, followed by filter pressing in the press 40, to separatecrystalline wax, then occurs. The chilling centrifuging, and solventseparating operations are then practiced in the order named, just asbefore described. Lighter colored products are produced from the stillbottoms 'of the still 10, when these are completely distilled.

While I prefer to use acid-activated clay in the still 10, I may usenaturally active adsorbent clay, or clay which activates easily in thepresence of sulphuric acid, even if the clay has no initial decolorizingpower. I may use a small percentage of concentrated sulphuric acid inthe still 10 during distillation, not to exceed two per cent by Weightof the clay used, whether activated or non-activated clay be present. Ifind that the presence of the acid assists decolorization and tends toimprove the quality of the oil.

Instead of acid being present I may substitute small quantities ofcertain salts resulting from the combination of a weak base and a strongCil acid. Examples are aluminum sulphate, magnesium phosphate andmanganese phosphate. No more than from 0.25% to 0.50% of such salts,calculated on the weight of the clay, should be present. These salts, Ihave ascertained, function as activators or catalyzers to fully developthe decolorizing action obtainable from the clays.

In the foregoing matter and in the appended claims, the Word bottomsmeans the heavy asphaltic, waxy, and adsorbent-containing residue ofdistillation of about 50% by weight of the wax slop, while the worddistillate means the total fractions distilled over, these consisting oflubricating oil and crystalline wax.

I claim as my invention:

1. A process of separating crystalline wax, amorphous wax andlubricating oil from wax slop which comprises: steam distilling amixture of adsorbent clay and wax slop in which there is a smallpercentage of an activating substance which promotes adsorption untilapproximately from fty to sixty per cent by weight of the charge hasbeen distilled over, slightly chilling the distilled fraction andseparating the wax therefrom, separating the clay from the bottoms ofthe distillation, diluting the bottoms with a light hydrocarbon,chilling the diluted bottoms to a low temperature to separate thecrystalline wax, ltering the separated wax from the ltrate chilling theltrate to a lower temperature, separating the amorphous wax and removingthe light hydrocarbon from the oil after the wax has been separatedtherefrom.

2. In a process of separating crystalline wax, amorphous wax andlubricating oil from wax slop the steps which comprise: diluting thebottoms of a steam distillation of said wax slop in the presence of anadsorbent clay with a light hydrocarbon, chilling the diluted bottoms toa low temperature separating the crystalline Wax, filtering theseparated wax from the clear bottoms, chilling the clear bottoms to alower temperature, and separating the amorphous wax.

3. In a process of separating crystalline wax, amorphous wax andlubricating oil from wax slop the steps which comprise: diluting thebottoms of a steam distillation in vacuo of said wax slop in thepresence of an adsorbent clay with a light hydrocarbon, chilling thediluted bot-` toms to a low temperature separating the crystalline wax,filtering the separated wax from the clear bottoms, and chilling theclear bottoms to'a lower temperature to separate the amorphous wax.

4. A process of separating crystalline wax, amorphous wax andlubricating oil from wax slop which comprises: steam distilling amixture of adsorbent clay and wax slop, the clay being present in theproportion of two to ten per cent of the slop, until approximately fiftyper cent by weight of the charge has been distilled over, diluting theltered bottoms with a substantial proportion of light hydrocarbon,cooling the mixture containing the ltered bottoms to approximately from30 F. to 60 F., filtering the mixture containing the filtered bottoms toseparate the crystalline wax, refrigerating the filtrate to atemperature sufficiently low to chill out substantially al1 of theremaining Wax, separating the wax, and then recovering the lubricatingoil.

5. A process according to claim 4 in which the adsorbent clay is a nelydivided acid activated clay containing free acid.

6. A process of separating crystalline wax, amorphous wax andlubricating oil from Wax slop which comprises: steam distilling amixture of adsorbent clay and wax slop, the clay being present in theproportion of two to ten per cent of the slop, until approximately fiftyper cent by weight of the charge has been distilled over, diluting thefiltered bottoms with a substantial proportion of light hydrocarbon,cooling the mixture to approximately from 30 F. to 60 F., ltering themixture to separate the crystalline wax, refrigerating the ltrate toapproximately 50 F. to chill out substantially all of the re-l mainingwax, separating the wax, and recovering the lubricating oil from thelight hydrocarbons.

7. In a process of separating crystalline wax, amorphous wax andlubricating oil from a wax slop the steps which comprise: steamdistilling a mixture of adsorbent clay and said wax slop, separating thecrystalline Wax and amorphous wax from the last forty to sixty per centof the said mixture by diluting said portion with a light petroleum oil,chilling the mixture to about 40 F. to separate the crystalline wax,ltering the separated wax from the mixture, refrigerating the ltrate toabout -50 F. separating the amorphous wax, and recovering thelubricating oil from the light petroleum oil after the wax has beenseparated therefrom.

8. A process according to claim 7 in which the ladsorbent clay is anacid-activated clay which contains a small percentage of an adsorptionpromoting substance.

9. A process according to claim 'I in which the distillation is carriedon as rapidly as possible and at as low a temperature as possible inorder to obtain a good separation of crystalline and amorphous wax.

WALTER S. BAYLIS.

